Treatment of fatty oils



Patented Jan. 19, 1954 TREATMENT OF FATTY OILS Arthur W. Hixson, Leonia, N. J., and Ralph Miller, New York, N. Y., assignors, by mesne assignments, to The Chemical Foundation, In-

corporated, New York, N. Y.,

New York No Drawing.

invention relates to the treatment of fattyfloils, more particularly to a method of devcolorizing and fractionating such oils. I This application is a continuation in part of prior application, Ser. No. 308,221, filed December 8, 1939.

, Crude fatty oils of commercial importance originate in living matter of diverse origin. Plant, animal and marine types of life contribute to the production of fatty oils. Irrespective of theirorigin, crude fatty oils are composed primarily of triglycerides, Fat has many important physiological purposes or functions andis always closely associated with other physiologically important materials in the living organism so that non-fatty materials are always present in a crude fatty oil from whatever source devised. From an economic standpoint it is desirable to secure large yieldsof fatty oils, hence in the, typical extraction methods much of the material naturally associated with it is present in the crude oils. Thus, while crude fatty oil is. composed primarily of triglycerides it contains many otherconstituents such as free fatty acids, resins, chromogenic substances, carbohydrates, albumin, .vitamins, sterols, hydrocarbons and the like. The range and complexity of the constituents which may accompany the triglycerides is illustrated, for example, by the qualitative composition of the minor constituents of crude cottonseed oil by Jamieson and Baughman (Oil and Fat Industry, Vol.3, p. 347 (1926)). These authors list the following constituents: Proteoses, peptones, phytosterols, phytosterolines, inosite phosphate, phospholipins resins, mucilaginous substances, carbohydrates, 1. e.,raflinoise and pentosans, pigments such as xanthcphyll, ,carotin and chlorophyll. The following ash-forming constituents were also reported by these authors to be present in the crude, pressed, filtered oil: Silica, phosphorus pentoxide, calcium oxide, magnesium oxide, potassium oxidasodium oxide and iron oxide. It is to be noted that the chemistry-of many of these substances is so complex' that they are described in general terms such as resins; which are dark-colored bodies.

Some of these constituents are dissolved in the oil while others are colloidally dispersed and many are objectional or undesired. The methods employed to process crude oils depend upon the use to which the refined oil is to be put.v Edible oils are usually extensively refined while. oils which are to be employed as soap stock receive but a modicum of refinement before saponification.

Application October 13, 1944, Serial No. 558,612

8 Claims. (Cl. 260-4285) a corporation of The methods currently employed for refining fatty oils consume considerable quantities of chemicals such as caustic soda, various bleaching agents, power steam and labor. Expensive equipment is needed because of the severe corrosive condition. Furthermore, the time required is protracted necessitating an inordinate investment for adequate capacity.

The discovery of the special and heretofore unknown correlation'of'the variationin solvent power of liquefied normally gaseous hydrocarbons with respect to predetermined fractions or constituents of crude fatty oil is of peculiar economic significance in the decolorizing of oils. As is known, for. certain purposes one of the most important properties of a fatty oil is its color. In most circumstances, if the color bodies of an oil, and particularly the color bodies of high tinctorial value, "1. e., dark or black color bodies, can be removed many of the other undesirable constituents are removed simultaneously. A measure of the undesirable constituents present in oil, other than color bodies, is the ash content.

'As has been explained previously, there are a variety of color bodies in crude fatty oils. It has been found that practically all the color bodies present in a crude fatty oil, except those of ayeiiowish cast, may-be removedby properly invoking the concept of the present invention, namely, utilizing the specific selective solubility of liquefied" normally gaseous hydrocarbons within controlled elevated temperature ranges.

' This finding is of definite and independent utility in the field of refining of fatty oils.

" As is known to those skilled in the art, the.

determination of the color of an oil is an empirical procedure. j

It is anobject of this invention to achieve clear cut separations of the principal classes of materialspresent in typical crude fatty oils. It is a further object of this invention to achieve these separations without consuming any reagents except through mechanical losses or leaking equipment. It is another object of the invention to effectively and simply decolorize fatty oils. It is a further object of this invention to secure higher yields and products not now avail able.

A method of processing crude fatty oils, to be rated highly efficient, should separate the raw material into at least four fractions: the free fatty acids, theltriglycerides, the complex materials, and ;the rnucilaginous constituents. The colloidally dispersed constituents are of a mucilaginousnature. 7 Those constituents which The. other class is composed. We have foundthat crude:

' Critical Critical Normally gaseous hydrocarbon temperpressureature, C. (atms) The various steps outlined hereinafter are allbased on the variation of the solvent properties. of liquefied, normally gaseous hydrocarbons with temperature with respect to the. constituents of crude fatty oils. The solvent power of a liquefled, normally gaseous hydrocarbon under its own vapor pressure is limited. when the temperature is 1n. the vicinity or considerably above the critical temperature of the hydrocarbon. This fact reveals the impracticability of using liquid methane for processing crude fatty oil's, as it would be necessary to Work at extremely low temperatures. It is more practical to use ethane than methane although the same. disadvantages are present, but not to the same degree. When propane is used, all the necessary separations can be carried out. between room temperature. and the temperature of boiling. water. This is the most convenientrange in which to work. Butane has the disadvantage of having its critical temperature considerably higher than. propane,v so that elevated temperatures are required. It is possible to use mixtures of. an these gases with. salutary results. Because. of' the convenience. offered by using propane, the methods used to process crude. fatty oils will. be described with propane as the liquefied, normally gaseoushyd'rocarbon.

Generally speaking, a substantive excess of solvent such as about 8 volumes. or more of propane per volume of fatty" oil is advantageous. Nov definite volume ratio can be assigned arbitrarily as best, or even as preferable, inasmuch as the ratio of volume of liquefied hydrocarbon" gas to volume of fatty oil that is" employa'ble' is a function of a great many variables. Among the variables are the composition of the solvent, the amount of impurity or. constituent present, the separation that is to be achieved, and the size of the equipment to be used compared to the volume of fatty oil to be processed. A little experience is all that isneeded to be" able to' select the correct volume ratio" indicated by the conditions presented.

We have found that much of the gummy material' present in crude fatty oils precipitates when the oil is dissolved inasubstantial volume of a liquefied, normally gaseous hydrocarbon. From 8- to' 10 volumes of propane to I of crude fatty oil may be employed. Previous investigators have formed solutions of fatty oils and liquid, normally gaseous hydrocarbons. In

spite of diligent efforts, we have failed to find a single instance Where a crude fatty oil was dissolved in a liquefied, normally gaseous hydrocarbon in such manner that the process could be visually observed; We have employed: a. Jerguson gauge: equipped with. glass Windows. plus the necessary auxiliary equipment to develop this invention. In this way, it has been possible to add av liquefied, normally gaseous hydrocarbon to a crude fatty oil and visually observe what happens... When the liquefied hydrocarbon at room temperature is slowly introduced into the gauge contai the crude fatty oil, it forms a; second liquid layer on top of the fatty oil. Upon gentle agitation, the crude oil is dissolved in: the hydrocarbon. Some resinous, mucilaginousrmaterials do not dissolve, for the final solution. is. turbid. The turbidity disappears on standing but reappears if the solution is disturbed. This phenomenon has not been observed hitherto. The mucil aginous, resinous materials can be separated fromthe oil by permitting the hydrocarbon solution tostand undisturbed until the insoluble material has settled and. then draining it' -otf- The rate at whichsettlingtakes; place is determined in part by the ratio of volume; of liquefied hydrocarbon to volume of crude oil. The higher the ratio,- the greater the rate. rate of settling can be increased. by maintaining. the solution at a constant. temperature. which is. slightly bGIOVF the: temperature atwhich. a second liquid phase would appear; This step effectively separates the mucilagi-nous: materials; from the other constituents of crude fatty oils..

The remainingconstituents of. crude fatty oils are all-- soluble in: eachother. This: fact. must be borne in mind-,- as it explains. the; necessity for reprocessing certain fractions in. order to. achieve substantially complete separations. Sterols occur in crude fatty oils to: only a limitedexten-t. We have found: that the. solubility of sterolmaterials in liquefied, normally gaseous. hydrocarbons varies with temperature. Sterolsv are only slightlysoluble propane at room temperature butthey are completely soluble in triglycerides; so that a mixture of triglycerides. and propane is abetter solvent. for sterols. thanv propane alone. This combination. of circumstances, the small quantity of. sterol. materials. present and the enhanced solventpower of a. mixture of propane and triglycerides; prevents the sterol materials from precipitating at room temperature.-

We have discovered thatthe. solubility of sterollike materials in liquefieda normallyv gaseous hydrocarbons decreases as the temperature is raised; Wehave also found that mixtures of liquefied, normally gaseous hydrocarbons and triglycerides which are composed primarily of" liquefied, normally gaseous hydrocarbons, similarly lose their solvent power'as-the temperature is raised. Qur novel process-for separating sterol-like ma.- terials from crude fatty oils-is based on this new discovery For example, when-the ratio of volume' ofpropane to volume of triglycerides. is 15 to I and the resulting solution is saturated at room temperature with a sterol -like material secured from the unsaponifiable fraction of a fishli-veroi l we have found that on heating the solution-under pressure 50 46 0., the sterol material. starts toprecipitate. 'When the sterol precipi-- tates; it will dissolve a small quantity of the triglycerides and fatty acids present. The sterol fraction will necessarily be impure However, it can be purified by repeating the propane treat- The ment The reason for somewhat impure sterol precipitating is understandable when the system being treated is considered. Essentially,-when the sterol fraction starts to precipitate, a twophase liquid system forms. One phase is the propane phase and the otherphase'is the sterol phase. The triglycerides and the fatty acids which are present are soluble in both phases. The manner in which they are distributed betweenthe two phases will vary with the respective volumes of each phase. The advantage of reprocessing the sterol phase is quite evident. Economic considerations determine the final purity of the sterol fraction. If an especially pure sterol product is desired, then the sterol fraction will be treated with propane several times. 'That is, the sterol fraction will be separated from the propane solution at a temperature between 40 C. and 60 C. I'he sterol fraction is then redissolved in an additional quantity of propane free from triglycerides and heated until the sterol dissolved in a liquefied, normally gaseous hydrocarbon precipitate at a lower temperature than fatty acids. This fact is important because it permits triglycerides to be readily freed from fatty acids. Crude fatty oils usually contain only a few per cent of free fatty acids, so that the commercial problem awaiting solution is the separation of a relatively small percentage of free fatty acids from triglycerides. This invention solves this problem readily. A liquefied, normally gaseous hydrocarbon is used to dissolve a mixture of triglycerides containing a few percent of' free fatty acids. The volume of liquefied, normally; gaseous hydrocarbon should be approximately '9 or more times the volume of crude fatty oil. The mixture is heated under pressure until most of the triglyceride has precipitated. Under the conditions described, when the liquefied, normally gaseous hydrocarbon is propane, it has been found-that practically all the triglycerideshave accumulated in the lower liquidphase when the temperature has reached 92 C. Although fatty acids precipitate above 92 0., the triglyceridesprecipitated below 92 0.,

are not completely free from fatty acids. The

fatty acids are completely soluble in the propane and in the triglycerides; This permitsthe free fatty acids to be} distributed between the triglycerides'and the propane in proportionto the volume occupied by each phase. Whenthe triglyceride phase is separated from the propane base, the free fatty acid concentration in the tri-' glycer'ides is decreased. The triglyceride phase may now be treated once more with fresh propane, decreasin the free fatty acid concentration still further. The process may be repeated as many times as is desired until the triglyceride is substantially free from fatty acids. The most efiicient method of eliminating free fatty acids from triglycerides employing liquefied, normally gaseous hydrocarbons in the mannerdescribed, is

'sible.

6" to use a'continuous countercurrent extraction system.

The foregoing methods have been'described in each case as though the crude fatty oil were to be divided into but two fractions. Previously, the statement was made that a highly efiicient method of processing crude fatty oils would permit at least four different classes of material to be separated from a crude fatty oil whose composition was sufficiently heterogeneous. To accomplish this quadruple division, it is only necessary to employ the principles of selective solvent fractionation described herein. It i practical, for" example, to dissolve a quantity of a crude fatty oil in about 10 or more volumes of propane. The solution may then be permitted to become quiescent and the insoluble material separated from the solution. The propan solution may now be heated up under its own vapor pressure to the neighborhood of 65 C. A second liquid phase will form. The two phases may be separated after Stratification has occurred. The propane solution may have its propane concentration adjusted to about 10 to 1 prior to further heating. The propane solution may now be heated up to 93 C. and the two resultant liquid phases separated. Each of these fractions may now be reprocessed with propane and the resulting similar fractions then blend and the blended fractions further processed. The four broad classes of material initially present will be effectually separated by this treatment.

This invention broadly contemplates the use of liquefied, normally gaseous hydrocarbons to effect separations of the type described. Innumerable combinations of steps forming. complete processes, all of which are useful, are pos- Crude fatty oils consist primarily of {nixed glycerides. We have found that by raising the temperature of a mixture of a crude fatty oil and a liquefied, normally gaseous hydrocarbon at a slow rate and in small intervals, it is possible to precipitate thetriglycerides a little at a time. In this way, triglycerides themselves may be fractionated. When the temperature is slowly raised, it is possible to produce a second liquid phase so small that it can just be seen. Y

A method of separating the four different types of material present in crude fatty oils has been described. In a great many instances, the type of oil being processed will determine exactly what fractionation will be carried out and which fractions'will be reprocessed. For example, one of the valuable constituents of crude soya bean oil is its phosphatide content. When soya bean oil is processed, the phosphatides are readily separated to a substantial degree from the oil by dissolving the triglycerides in a liquefied, normally gaseous hydrocarbon. The phosphatides are insoluble in such a medium, so that it is only gaseous hydrocarbons with respect to predetermined fractions or constituents of crudefatty oils is of peculiar economic significance in the decolorizing of oil.- As is known, for certain purmeans poses aone ofithe mostimportant properties :of -a fatty oil is its color. It has been found .thatin practically every instance if the-color bodies of an oil, and particularly those xcolor bodies which are very :darkor black, can be removed 'many of the other undesirable constituentsof an oil are removed simultaneously. A measure of the un desirable constituents present in an oil, other than color, is the'ash contentof the oil. As will be seen more fully :hereinafter by invoking the principles of this invention rapid and effective decolorizingmay beachieved with minimal losses Qfoil.

The removal :of color is an important -factor in the refining of many oils. For example, the removal'of color and fatty acids are the principal'objectives in the refining of edible oils. Similarly, color removal from drying oils i highly desirable. Only a relatively small quantity of chromogenic materials are present in most crude fatty oils butthesemaybe of such high tinctorial value as to impart a substantialcolor to the oil.

As has been pointed-out previously there .are a variety of color bodies in crude fatty oils. It has been ascertained that practically all of these color bodies can be removed by methods to be described except those of a yellowish cast. It appears that the ash does not accompany this type of colorbody.

The novel process of decolorizing is based upon normally gaseous hydrocarbon at a temperature above the miscibility temperatures of such triglyceride fraction.

In .commercialoperations propane is the preferred .solvent although,.as pointed out previously, mixtures of ethane, propane and butane .as well as the olefins of this series may be used. The effective decolorizing of fatty oils stems from a study of the effect of varying the temperature of a solution of crude fatty oil in propane. It was found that when a solution comprised of 1 part of fatty oil and about 10 parts of propane was heated somewhat above room temperature the hydroearbonno longer was completely miscible with the oil and two liquid phases formed. It was further ascertained that the first small fraction of oil which came outofsolution to form the second lower liquid phase contained greatl-y more than its proportionate share of colorbodies. The .novel decolorizing method i based on these fundamental findings; It is particularly to be observed at this point that this extraction of color by concentrating it in a lower liquid phase containing a very small fraction of the totaloil is .to be distinguished sharply from methods which involve the treatment of an oil with a liquid hydrocarbon at room temperature. .In such methods .a separation .of gummy material is achieved but the material which is separated i only that which is normally insoluble in the hydrocarbon. Such methods do not invoke the principle of concentration of color inan oil fraction which forms .a lower separate phase .at a predeterminedelevated temperature.

It is apparent that acommercially efficient-process should effect .a concentration-of substantially all the color bodies in a very small percentage or fraction of the total oil. .As will be :seen, the present process abundantly satisfies the requirement. In carrying out the process the crude fatty .oil is contacted with the solvent, .such as liquefied g-propane, :at :a temperature which is slightly above the miscibility temperature for the particular oil, solvent "and ratio -.of oilto solvent. In these circumstances, allebut :a minor fraction .of the oil is dissolved in the solvent. The undissolved oil appearing as thelower separate liquid phase contains substantially all of the colorbodies and some of the solvent. These phases are readily separated and by removing the solvent associated with-each phase the original oil is separated into :two fractions; one which is highly concentrated in color bodiesand-the other which is enriched in triglycerides andcontains but a minor amount of color bodies.

The following examples illustrate the eificacy of the new process:

The operations to be described were carried out in a packedtower :20'feet high which was provided with means for controlling the temperature throughout the length of the tower. Oil was pumped intothe upper portion-of .the tower and propane into the :lower portion at such selected rates as to obtain the desired ratesof solvent to oil. The ,propane employed was stored in a closed vessel underitown vapor pressure and-Was pumped from the storage vessel through a heat exchanger and then :into the tower a few feet aboveits base. Byutilizing suchheat exchanger the temperature of the propane entering the tower maybe readily controlled. The crude oil similarly was pumped througha heatexchanger and into the tower a few afeet below the top of the tower. The distances between the propane inlet and oil inlet could be varied as Well asthe distance of the inletof each from the base of the tower. The tower operated :under the vapor pressure of propane at the prevailing temperature plus a superimposed pressure of about pounds, to insuresmooth operation. The necessary stills, condensers and compressors for removing and recoveringthe solvent were employed in the conventional manner.

EXAMPLE I A quantity of a high grade, crude, pressed filtered linseed oil was pumped into the tower at a point about .2 feet from the top. Fifteen volumes of propane per volume of oil was pumped .into the tower at a point 2 feet from the base. The top of the tower was maintained at .a temperature of 58 'C.; at the oil inlet the temperature was about 56 C. and the temperature at the bottom of the tower was 54.5 C. The lower immisciblephase constituted 8.7% of the charge oil and the upper propane phase'leaving the tower contained 913% of the charge oil.

The "bottom 8.7% fraction was rerun in the tower using a solvent to oil ratio of to 1 and the temperature-of'the mixture was 495 C. The lower liquid phase which was withdrawn'represented 2% of the original 'oil. The overhead from this rerun was-combined with the first overhead fraction. The following table shows the results of this treatment.

It will be observed-that the color of the original '9 oil is quite light-for a crude oil. The efliciency of the process with respect to color and ash concentration is readily apparent. The 2% bottom fraction was black in color showing a high removal of color bodies. This particular color measurement, as indicated in the table, is too insensitive to accurately measure the decolorizing action. v

' EXAMPLE II The sample of linseed oil used in'Example I contained .8% free fatty acid. Thisoil was dissolved in 5 volumes of propane and the propane solution was intimately mixed with the theoretical quantity of 4N KOH. The propane solution and the alkali were mixed continuously and the mixture was passed continuously to a settler in which the soap settled out. The clear overflow was pumped to a still to separate the propane from the neutralized 'oil. The original oil had a color of 11 on the Gardner-Holdt scale and an ash content of 154%. The neutralized oil contained .06% free fatty'acid, had an ash content of .157% and a color of 11 on the Gardner-Holdt scale.

The preceding example proves conclusively that in the case of a typical filtered crude oil neither the color nor the ash content can be reduced by simply diluting'with propane and affording the solution suitable time for settling. As will be observed, there is no comparison between the color removal eifected by positively establishing a second liquid phase, in the manner described in Example I, and simple dilution with propane. lished the fact that to secure effective color removal the process must be carried out at a sufficiently high temperature to insure the Presence of a second liquid phase.

EXAlMPLE III A sample of sardine oil was treated in the described apparatus with propane under the following conditions. The ratio of solventto oil was 30 to 1 and the temperature in the tower was 76 C. In this particular operation the overhead was stripped of propane and for every 12 parts of oil that came overhead, 11 werepumped back into the tower as a reflux. Under these circumstance the oil was split into an overhead fraction consisting of 11.8% of the original oil and bottoms fraction consisting of 88.8% of the original oil. The bottom fraction was rerun in the tower under the following conditions: the ratio of propane to charged oil was 30 to l; and the temperature was maintained at 67 C. and the reflux ratio was 3.1 to 1. The overhead fraction represented 27.2% of the charge on and the bottoms represented the balance. The color of the charge oil was 9 on the Gardner-Holdt scale. The first overhead fraction, of 11.8%, had a color of 4. The first bottom fraction had the same color as the original oil. However, the second overhead fraction had asurprisingly lowcolor of 1 while the second bottom fraction had a color of 12. These results indicate clearly how effectively the color bodies may besegregated, especially after those color bodies having a yellowish cast are removed in a preliminary step.

EXAMPLE IV Numerous experiments have estabhigh molecular weight substances.

Table II Overhead Bottoms Charge 2 :3 2,? 3.2%? yield, yield,

' percent percent Raw soybean oil... 76 30 1 5 95% bottoms 72 2 1 46.1 53.9 53.9% bottoms 74 31 85.7 14. 3

The four fractions of Table II can, for convenience, be identified as the 5% overhead, 46.1% overhead, 85.7% overhead and the 14.3%bottoms. The color and ash content of these fractions were determined and are shown in the following table:

Table III Percent It is particularly to be observed that the ashforming constituents were concentrated in the final bottoms along with the dark color bodies. It is similarly interesting to observe that all the overhead fractions, although containing a small amount of color are free from ash. In view of the fact that little is known of the color bodies in oil it is impossible to identify the color bodies which go overhead. However, in most cases, they are present in but a minor degree and are not very objectionable.

It will be clearly apparent from the foregoing examples that the color bodies in fatty oils may readily be segregated by utilizing a liquefied, normally gaseous hydrocarbon when such solvent is used according to the principles outlined. These desirable results can only be obtained, as explained, by elevating the temperature of the system to that point which insures the presence of the second liquid phase. As a result of extensive experimentation it has been found that crude fatty oils of every class, animal, vegetable and marine oils are amenable to the described treatment.

As indicated previously, the principles of the invention may be utilized to treat fatty oils for diverse types of separation or fractionation. An additional example of the wide availability of the improved process is in the treatment of heat bodied oils. As is known, some fatty oils are heat bodied before being used in paints. This heat bodying process causes a certain amount of polymerization. It is frequently found desirable to separate the unpolymerized material from the It has been ascertained that the polymerized material is practically insoluble in liquefied, normally gas= eous'hydrocarbons. By employing the technique heretofore described the heat bodied oils may be readily fractionated so as to'separate the partially polymerized oil with high molecular weight fractions and low molecular weight fractions.

It will be seen that the processes comprehended under the present invention are as effective as they are simple. The process comprises essentially contacting crude fatty oils with an adequate volume of a liquefied, normally gaseous hydrocarbon under predetermined elevated temperature conditions which insure the formation of a second liquid phase. Such second liquid ace-637s phase is more dense than the hydrocarbon phase and forms a lower layer. The lower layer consists predominantly of substances only slightly soluble in the hydrocarbon phase in addition to some dissolved hydrocarbon. The upper. phase is composed of the liquefied, normally gaseous. hydrocarbon in which the remaining constituents of the fatty oil are dissolved. As fully explained herein the constituents which are segregated in the lower phase are primarily determined by the type of oil treated, the oil to solvent ratio and the temperature of phase formation. By control of these factors different degrees of separation may be secured extending from simple decolorizing to plural fractionation into four separate fractions. The phases which are formed in the countercurrent extraction system are separated and the hydrocarbon content recovered from each phase. The recovered solvent" may be recycled continuously in.the system.

It will be understood that in operating under the invention the ratio ofliquefied, normally gaseous hydrocarbon to the volume of fatty oil must be adequate for the particular separation desired. While certain specific ratios have been mentioned it is. to be understood that these are given as illustrative and not as limiting values.

As has been described previously, at normal or room temperature the oil is soluble in, or miscible with, liquefied normally gaseous hydrocarbons to a predetermined degreeor extent depending upon the type of oil and hydrocarbon in the system. This solubility, for simplicity, is defined in the claims as that obtaining at normal miscibility temperature. It will be. understood that whenever the expression, liquefied. normally gaseous hydrocarbon; is used in the claims it comprehends both single hydrocarbons andimixtures of such hydrocarbons.

While. preferred modificationsof the invention have been described it isto be understood that these are given didactically to illustrate the underlying principles involved and. not as limit.- ing the'useful scope of the invention to the particular processes described.

We claim:

1. The process of treating with liquefied, normally gaseous, hydrocarbons, a crude. fatty oil containing triglycerides, mucilaginous materials, andcomplex materials, consisting. in dissolving the oil in a liquefied, normally: gaseous, hydrocarbon in which the mucilaginous material is not soluble; separat-ing'thetwo resultant phases; heating the hydrocarbon solutionunder pressure until a second liquid phase appears; maintaining the temperature constant until the two phases have stratified; separating the'upper liquid phase from the lower liquid phase; recoveering the hydrocarbon associated with each liquid phase, and repeating. the treatment as to each residual phase by elevation of temperature whereby the mucilaginous constitutents, thecomplex: materials,. substantially free from triglycerides, and triglycerides substantially free from complex materials, become separately recoverable as final products.

2. The process of dividing a crude fatty oil into four fractions, consisting in dissolving the oil in a liquefied, normally gaseous, hydrocarbon in which the mucilaginous materials are not soluble and separating the hydrocarbon solution from the insolubles; heating the solution to a temperature of the order of 65 C. until a second liquid phase forms; maintaining the temperature constant until the phases stratify; separating the lower phase from theupper" phase; the lower phase containing most of the complex material contained in the original oil; heating the upper phase to a higher temperatureof the orderof 92C. until another substantial phase appears; maintaining the temperature constant so that the phases stratify; separating the lower phase from the upper phase; the lower phase being composed primarily of triglycerides, the upper phase containing most. of the free fatty acids present in the original oil recovering the hydrocarbon associated with each phase and continuing the treatment on each fraction to produce four final fractions; namely; the" mucilaginous materials, the complex' materials, the triglyceridesand the free fattyacids, each fraction being substantially free from" of the components ofthe other fractions;

3. The process of? fractionating'a crude mixture oftriglyceride's' and free" fatty acids consist ing'inv dissolving themixture in a' liquefied, normally gaseous hydrocarbon; heating the. solution under pressure until a substantial second liquid" phase appears"; maintaining the temperature constant until the. two phases. stratify; separating the lower phase from the upper phase; recovering thehydrocarbon associated with each phase and thereby producing. two fractions; the fraction obtained from the lower phase being richer in triglycerides than the fraction obtained from theupper phase; and repeating the operation-upon each residual fraction by elevation of temperature until a triglyceride fraction, substantialyfree from fatty acidsis produced;

4. The process of refining a. crude fatty oil composed of triglycerides; free fatty acids and mucila'ginous' materials comprising dissolving the oil ina liquefied; normally gaseous hydrocarbon in which the mucilaginous material isnot' soluble; separating the mucilaginous material from the solution; heating the hydrocarbon under pressure until a second liquid phase appears which contains a substantial amount of triglycerides and which contains relatively less fatty acids'than the original oil; separating the two phases, andrecoveringthe hydrocarbons associated'with each phase andrepeatin'g the treatment as'to each residual phase by elevation of temperature whereby mucilaginous constituents, a triglyceride fraction substantially free from fatty acids an'da fatty acid'fraction substantially free from triglycerides are independently established.

5. The. process of decolorizing and de-ashing naturally occurring unbodied crude fatty oils containing a mixture of triglycerides and natural- 1y. occurring fat-soluble color bodies which mixture is soluble in liquid propane, at atmospheric temperature which comprises, contacting the oil with a liquefied, normally gaseous hydrocarbon at an elevated temperature;,the ratio of liquefied hydrocarbon. to oil. and the: contacting, temperature being selected to form two liquid phases differing in. density, such contacting temperature being. but slightly above the highest temperature at. which the crude oil andliquefied hydrocarbon are completely miscible, at the selected ratio of contacting temperature. at. the selected ratio. of liquefied hydrocarbon to oil, maintaining said liquefied hydrocarbon. to: oil'jso that the less dense phase so formed and maintained contains not less than 95% of the triglycerides of the crude fatty oil and the majorportion ofthe liquefied hydrocarbon and themore dense phaseso formed and maintained contains not more than 5% of 13 the triglycerides and the remainder of the hydrocarbon and substantially all of the color bodies and a preponderant amount of the ash-forming constituents and separating the more dense phase from the less dense phase.

6. The process of decolorizing and de-ashing naturally occurring unbodied crude fatty oils containing a mixture of fatty acids, triglycerides and naturally occurring fat-soluble color bodies which'mixture is soluble in liquid propane at atmospheric temperature which comprises, contacting the crude oil in a continuous counter-current extraction system with liquid propane at an elevated temperature, the ratio of propane to oil and the contacting temperature being selected to form two liquid phases differing in density, such contacting temperature being but slightly above the temperature at which the crude oil and the liquefied propane are completely miscible at the selected ratio, maintaining such contacting temperature, at the selected ratio of liquefied propane to oil so that the less dense phase so formed and maintained contains not less than 95% of the triglycerides of the crude oil and the major portion of liquefied propane and the more dense phase 50 formed and maintained contains not more than 5% of the triglycerides of the crude oil and the remainder of the propane together with substantially all of the color bodies and a preponderant amount of the ash-forming constituents of the crude oil, and separating the more dense phase from the less dense phase.

7. A method of. decolorizing and de-ashing crude, unbodied linseed oil which contains the naturally occurring, fat-soluble color bodies in substantially unaltered form which comprises, contacting the oil with liquid propane in an approximate proportion of about 1 volume of oil to 15 volumes of propane at an elevated temperature selected to formtwo liquid phases differing in density, such contacting temperature being but slightly above the highest temperature at which the oil and propane are completely miscible at the selected ratio, maintaining such contacting temperature, at the selected ratio of propane to linseed oil, so that the less dense phase so formed and maintained contains not less than 95% of 14 the triglycerides of the oil and the major portion of the liquid propane and the more dense phase so formed and maintained contains not'more than 5% of the triglycerides of the oil and the remainder of the propane and substantially all of the color bodies and a preponderant amount of the ash-forming constituents of the original linseed oil; and separating the more dense phase from the less dense phase.

8. A method of decolorizing and de-ashing a naturally occurring, unbodied, crude fatty oil containing a mixture of triglycerides and natural- 1y occurring, fat-soluble color bodies which mixture is soluble in liquefied propane at atmosits) pheric temperature, which comprises, contacting the oil in a continuous countercurrent extraction system with liquid propane inthe proportion of 1 volume of oil to 15 or more volumes of propaneat an elevated temperature selected to form two liquid phases differing in density, such contacting temperature being but slightly above the highest temperature at which the crude oil and propane are completely miscible at the selected ratio, maintaining such contacting temperature, at the selected ratio of propane to oil so that the less dense phase so formed and maintained contains notless than 95% of the triglycerides of the crude oil and the major portion of the propane and the more dense phase so formed and maintained contains not more than 5% of the triglycerides and the remainder of the propane and substantially all of the color bodies and a preponderant amount of the ash-forming constituents; and separating the more dense phase from the less dense phase.

ARTHUR W. HIXSON.

RALPH MILLER.

References Cited in the file of this patent UNITED STATES PATENTS 

5. THE PROCESS OF DECOLORIZING AND DE-ASHING NATURALLY OCCURING UNBODIED CRUDE FATTY OILS CONTAINING A MIXTURE OF TRIGLYCERIDES AND NATURALLY OCCURRING FAT-SOLUBLE COLOR BODIES WHICH MIXTURE IS SOLUBLE IN LIQUID PROPANE AT ATMOSPHERIC TEMPERATURE WHICH COMPRISES, CONTACTING THE OIL WITH A LIQUEFIED, NORMALLY GASEOUS HYDROCARBON AT AN ELEVATED TEMPERATURE; THE RATIO OF LIQUEFIED HYDROCARBON TO OIL AND THE CONTACTING TEMPERATURE BEING SELECTED TO FORM TWO LIQUID PHASES DIFFERING IN DENSITY, SUCH CONTACTING TEMPERATURE BEING BUT SLIGHTLY ABOVE THE HIGHEST TEMPERATURE AS WHICH THE CRUDE OIL AND LIQUEFIEC HYDROCARBON ARE COMPLETELY MISCIBLE AT THE SELECTED RATIO OF LIQUEFIED HYDROCARBON TO OIL, MAINTAINING SAID CONTACTING TEMPERATURE AT THE SELECTED RATIO OF LIQUEFIED HYDROCARBON TO OIL SO THAT THE LESS DENSE PHASE SO FORMED AND MAINTAINED COINTAINS NOT LESS THAN 95% OF THE TRIGLYCERIDES OF THE CRUDE FATTY OIL AND THE MAJOR PORTION OF THE LIQUEFIED HYDROCARBON AND THE MORE DENSE PHASE SO FORMED AND MAINTAINED CONTAINS NOT MORE THAN 5% OF THE TRIGLYCERIDES AND THE REMAINDER OF THE HYDROCARBON AND SUBSTANTIALLY ALL OF THE COLOR BODIES AND A PREPONDERANT AMOUNT OF THE ASH-FORMING CONSTITUENTS AND SEPARATING THE MORE DENSE PHASE FROM THE LESS DENSE PHASE. 